3D Numerical Modelling of Salt Tectonics

Many factors have been suggested to affect the development of salt structures, including sedimentation, brittle sediment deformation, multiple tectonic events and basement topography. To unravel the relative importance of these processes, we performed high resolution 2D and 3D thermo-mechanical simulations that take these factors into account, while incorporating nonlinear salt creep laws and visco-elasto-plastic rock properties. Simulations show that the sedimentation rate affects both the speed with which structures form, and the spacing between the salt structures, which is larger for higher rates. Consistent with earlier sandbox experiments, we find that there is a feedback between localized fault formation in the overburden and the growth of salt structures, which form easier for larger salt thicknesses. 3D models are largely consistent with 2D results, but show that even an extended 2D setup (homogeneous in the 3rd dimension) can result in 3D salt structures during a tectonic reactivation phase. Our study shows that it is now becoming possible to perform numerical models of salt tectonics on a routine basis, which can be tuned to specific target areas to guide physics-based tectonic interpretations.